US20050015368A1 - Query modelling tool having a dynamically adaptive interface - Google Patents

Abstract

A user-friendly query modeling tool and method, for representing, creating, modifying and modeling a query language statement for use in retrieving data from a database. In accordance with the present invention, the tool includes a user interface for receiving or building and manipulating a query, a query model definition for use in populating instances of one or more query models, and a model content provider for receiving query elements from the user interface and providing them to the query model, and conversely, for retrieving query elements from the query model and providing them to the user interface. The user interface dynamically adapts to selections by a user in creating or editing a query statement, thus providing a helpful and user-friendly visual interface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• The present application is related to the following patent applications which are commonly assigned and filed on the same day, Jul. 15, 2003: SVL920020046US1, application Ser. No. ______, entitled “Model Content Provider With Reusable Components for Supporting a Plurality of GUI APIs”; SVL920020047US1, application Ser. No. ______, entitled “Query Model Tool and Method for Visually Grouping and Ungrouping Predicates”; and SVL920020048US1, application Ser. No. ______, entitled “A Method and Structure for Representing Complex Query Elements in a Modelling Tool.”
FIELD OF THE INVENTION
• This invention relates in general to database management systems performed by computers, and in particular, an interactive tool and method for graphically representing, creating, modifying and modeling structured language queries.
BACKGROUND OF THE INVENTION
• Databases are computerized information storage and retrieval systems. A Relational Database Management System (RDBMS) is a database management system (DBMS) which uses relational techniques for storing and retrieving data. Relational databases are organized into tables which consist of rows and columns of data. The rows are formally called tuples or records. A database will typically have many tables and each table will typically have multiple tuples and multiple columns. The tables are typically stored on direct access storage devices (DASD), such as magnetic or optical disk drives for semi-permanent storage. Data stored in a database is selectively retrieved using a database query.
• The data from a relational database is commonly retrieved using a Structured Query language (SQL) interface which is well known in the art. The SQL interface has been adopted as such by both the American Nationals Standard Organization (ANSI) and the International Standards Organization (ISO), and allows users to formulate relational operations on the tables interactively, in batch files, or embedded in host languages such as C, COBOL, etc. Operators are provided in SQL that allow the user to manipulate the data, wherein each operator operates on one or more tables and produces a new table as a result.
• Query languages such as SQL require some expertise to write effectively. Since both users and applications heavily rely on query statements for retrieving information, tools have been developed to assist in the creation of query statements. These tools include a user interface for creating the initial query, and a query model for storing the components of the resulting query in a manner that enables their reconstruction. Once completed, the query is forwarded to the database management system for performing selective data access.
• Query tools suffer from numerous shortcomings that have highlighted a need for a more useful and user-friendly query building tool. The assistance they provide is limited to basic query syntax, requiring manual input of more complex queries. Further, while existing query tools enable creation and modification of new query statements, they do not generally provide means for populating the interface and underlying model with existing query statements to enable modification of those statements.
• Other shortcomings exist in the query models themselves. For example, existing models provide limited representation of complex query elements in formats that are not readily understandable to the developer. Moreover, they do not provide much flexibility for reconstructing the query and its subelements. In addition, they are often dependent upon the format of a particular user-interface and do not lend themselves well to use by graphical user interfaces of different formats.
SUMMARY OF THE INVENTION
• In response to the shortcomings of prior query generating tools, the present invention is directed to a user-friendly interactive system and method for representing, creating, modifying and modeling a query language statement for use in retrieving data from a database. According to the system and method of the present invention, a tool is provided that includes an interactive graphical user interface for inputting, creating, and modifying database query statements. The tool further provides an application interface for enabling receipt and manipulation of existing query statements. A modeling schema is defined for storing the query statement elements. The modeling schema provides a high granularity, meaningful representation of complex query elements reflective of the query syntax. As one aspect of the invention, the modeling schema reflects multiple dialects of the query language by representing element types and subtypes from all dialects considered in creating the schema. In a further aspect of the invention, the granularity of the modeling schema enables reconstruction of the query statement or any element thereof with a single call to a node representative of that element. The call returns not only the element represented by the node, but also all elements represented by subnodes of the node.
• In one aspect of the invention, queries can be built directly by a user through a user-interface, or by an application through an application programming interface.
• In another aspect of the present invention, the interface and model may be populated by newly created query statements, existing query statements, or both.
• In a further aspect of the invention, nested search conditions may be created and manipulated through the graphical user interface and the resulting query represented in an understandable manner.
• In another aspect of the present invention, the interface is dynamically adaptive to the query element being constructed.
• In another aspect of the present invention, any sub-element of a stored query statement may be reconstructed inclusive of all of its child elements.
• In a further aspect of the present invention, the query model represents query elements that have historically been difficult to model in a granular and understandable fashion, such as group-by's, predicates, table references, value expressions and iterative and nested elements. In particular, the query model comprises atomic, hierarchical representations of all desired query elements, taking into account the various dialects of the query language, so that any incoming query can be stored within its schema.
• In yet another aspect of the invention, a layer comprising a common set of generalized classes is provided between the user interface and the query model for use in retrieving data from the query model and populating user interfaces of different formats.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a simple block diagram of the Query Assist tool of the present invention.
• FIG. 2 is a block diagram illustrating the architecture of the Query Assist tool of the present invention.
• FIGS. 3A and 3B illustrate an exemplary user interface for use with the Query Assist tool of the present invention.
• FIGS. 3C and 3D are flow diagrams representing user and system actions when using the interface ofFIGS. 3A and 3B.
• FIG. 4 is a block diagram representing the model content provider of the present invention.
• FIG. 5 is a flow diagram illustrating the steps for modeling a query according to the present invention.
• FIGS. 6A and 6B illustrate a combined structure for modeling complex queries including an atomic element and a combined query element according to an aspect of the present invention;
• FIGS.7 to10 illustrate model representations of various complex query elements using the combined structure ofFIGS. 6A and 6B;
• FIG. 11 is a representation of a query sub-statement populating an instance the model according to the present invention; and
• FIG. 12 is a block diagram representing an approach for removing dependencies among models created in different domains.
DETAILED DESCRIPTION
• The present invention will now be described with reference to a specific embodiment. However, it will be understood that various modifications and equivalent substitutions may occur to an implementer of the tool described without parting from the spirit and scope of the invention. Accordingly, the invention is not intended to be limited in any manner by the specific embodiment, and each element described is intended to encompass all reasonable equivalents thereof.
• I. System Architecture
• FIG. 1 represents a system suitable for practicing the present invention. It includes relational database management system software (RDBMS)10 residing in aserver12 and coupled to adata storage unit11. TheRDBMS10 of the present invention is the IBM® DB2®, relational database product, although any relational database may be substituted. The server of the present invention may be, for example, IBM's UNIX-based pSeries™ server, Intel-based xSeries™ server, AS/400 based iSeries™ server, or OS/390 based zSeries™ mainframe running the compatible DB2 software. It may also be any hardware configuration capable of providing a suitable environment for running relational database software accessible by an application. Thestorage11 may be any type of persistent storage such as an array of direct access storage devices, optical drives, holographic devices, tape, etc. and may be accessed via a network connection, SCSI bus, or otherappropriate means15. TheRDBMS10 of the detailed embodiment is accessed byapplication software16 residing on aclient workstation18. Alternatively, it may run within the application space of a mainframe computer. Theapplication software16 makes requests to theRDBMS10 for information and data over aconnection15 which may be, for example, an internet connection, a communications bus, or other appropriate accesses means. Requests for information and data are typically in the form of a relational database query statement sent overconnection15 to the RDBMS. The RDBMS parses the query statement for processing, and writes, modifies or retrieves data fromstorage11 in accordance with the query statement's content. Thequery assist tool14 of the present invention is software residing between theapplication software16 and theRDBMS middleware10. According to the detailed embodiment, it resides onclient18, but it may also reside on a separate machine such as theserver12, as long as it is accessible by theapplication16, e.g. via a network or TCP/IP connection.
• FIG. 2 is a detailed block diagram representing the query assisttool14 ofFIG. 1. It includes auser interface20 for assisting a user in creating and modifying a query statement, an application interface (API)22 for receiving query statements such as embedded queries directly from an application, aparser24,GUI model infrastructure28 and aquery model26.
• Theuser interface20 may be incorporated into an application, thereby enhancing the application interface with query building capabilities. Alternatively, the interface may be part of a separate query building tool.
• Theapplication interface22 is coupled to aparser24, as represented byarrow27.Parser24 receives the query statement and decomposes it into subelements or model elements (objects) based on the parsing rules. The parsing rules include syntactic rules and semantic rules. The syntactic rules break down the query into syntactic elements that form the basis for creating a query model representation. The semantic rules enable the parser to create and relate the model objects according to the model definition. These semantic rules will be described in further detail subsequently. The parsed statement is then forwarded to a memory-basedquery model26 for storage as represented byarrow29. Theparser24 may also forward the model elements to theuser interface20. Consequently, queries received throughAPI22 may be modified viauser interface20.
• Interface20 also communicates withquery model26 viaGUI model infrastructure28, as represented byarrows19 and21.Interface20 is designed to be consistent with the query model definition. Accordingly, when a query is created usinginterface20, the interface creates and relates model elements that conform to the query model definition. The queries may be used to populate the model directly as represented byconnection21 without further parsing.
• Theuser interface20 may also include a query input allowing the user the option of typing in a query statement. Such queries are first sent through theparser24 so that the model elements and relationships may be created in the same manner as queries received overAPI22. In addition, the user interface of the present invention includes an expression builder which allows a user to type in complex sub-expressions. These sub-expressions are similarly passed to the parser overconnection25 prior to being stored in thequery model26.
• II. User Interface
• FIGS. 3A and 3B are screen captures of a user interface suitable for practicing the present invention. As persons familiar with database querying will appreciate, typical query comprises a SELECT-type clause having a format like the following:
• • SELECT column_list
  • FROM sourcetable_list
  • optional WHERE search_condition
  • optional GROUP BY columname_list HAVING search_condition
  • optional ORDER BY columname_list
    Although the interface ofFIGS. 3A and 3B are illustrated with reference to the SQL syntax, it will be understood that the invention is not limited to queries written in SQL, but can be applied generally to any query language.
• The interface portion of the query building tool may be implemented using any known interface generating tool or programming language such as, for example, Visual Basic or Java.
• As illustrated inFIG. 3A, the query building tool of the present invention provides an interface for building a query by providing a set of display areas for specifying query elements. In afirst OUTLINE region30, elements of a query statement are represented in an outline format as shown. A general header is entitled “Statement Properties”. Under this heading is a category entitled “SELECT statement”, and all supported elements of a SELECT clause are listed as its subcategories, e.g., “FROM”, “WHERE”, “GROUP BY”, “HAVING” and “ORDER BY”. The user begins construction of a SELECT statement by opening the “Select statement” folder to display the subcategories. He then proceeds to select one of the displayed subcategories, e.g., by highlighting his selection with a mouse, and specifying the parameters of that subcategory in theinput region32 and/or38.
• Alternatively, the interface may be populated with an existing query statement stored in the underlying query model. This is achieved by each portion of the interface retrieving and displaying the elements of the underlying query model that are appropriate for that portion.
• The “Details”section32 enables the user to specify the parameters for his selected subcategory. The format ofregion32 changes for each subcategory selection made inregion30. For example, if the user selects subcategory “FROM”, the interface makes a call to the underlying database for a list of available source tables, and then displays these as selectable options. The user then selects from the displayed tables, e.g., by highlighting. Similarly, if the user selects the “SELECT” subcategory, thedetails region32 displays the columns of the selected table(s) for further selection by the user. Selection of the “WHERE” subcategory causes the “Details” section to display a “Predicate”region34 and a “Search Conditions”region36 as shown.
• Thepredicate region34 allows the user to build one or more predicates by selecting an operator (AND, OR or NOT) usingbuttons31A and31B for connecting multiple predicates, acolumn name33, acolumn operator35, and anoperator value37, e.g. by pull down menu, field select or other comparable means. The resulting predicate is displayed in editingwindow38 and “Search condition”window36, described in more detail subsequently.
• As an aspect of the present invention, the format of thevalue input area35 in thepredicate region34 changes dynamically in response to selection of acolumn operator35. For instance, inFIG. 3A the column operator selected is an equals sign (=). In response to that selection the screen definition is modified to display a single value pull down menu inregion37. The pull-down menu lists all possible values for thecolumn name33 “JOB” specified by the user.
• Another example of the dynamic aspect of thepredicate region34 is shown inFIG. 3B. Here, the user has selected acolumn name33 of “HIREDATE” from a list of possible options, and the “BETWEEN”column operator35. In response, minimum and maximum value input regions are displayed ininput area37. The selectable minimum and maximum values represent all possible values of column “HIREDATE”33.
• When all predicate options have been specified infield34, the user confirms his selection, e.g. by clicking his mouse onbutton39. Confirmation causes the query model to be populated or updated with the new predicate as previously described. It also causes the new predicate to appear in searchcondition display area36 and in “SQL code” editingwindow38.
• In the example ofFIG. 3A, three user-specified search conditions are displayed in region36: “EMPLOYEE.WORKDEPT IN (‘E01”, ‘E11’, ‘E21’)’”; “EMPLOYEE.JOB=‘MANAGER’”; and “EMPLOYEE.JOB=‘SALESREP’”. They are connected by operators “AND” and “OR”, respectively.
• Another aspect of the present invention is the ability to group or nest predicates inregion36 to control the order in which they are evaluated. InFIG. 3A, the user has elected to group “EMPLOYEE.JOB=‘MANAGER’”; and “EMPLOYEE.JOB=‘SALESREP’”, as indicated by the parenthesis around these predicates and their indentation with respect to the “EMPLOYEE.WORKDEPT IN (‘E01’, ‘E11’, ‘E21’)” predicate. Grouping is effected by highlighting the desired predicates inwindow36 and then clicking on “( . . . )button41. The action of clicking onbutton41 again causes the parenthesis and indentation, or similar indicia of grouping, to appear inwindow36. It also causes the query model to be updated with the change to the displayed search condition. Grouped predicates may also be ungrouped by highlighting a set of grouped predicates and clicking on ‘Remove’button43.
• The grouping function described above is illustrated by flow diagram3D. In afirst step91, the user select rows insearch condition area36 such that first and last rows are at same level of indentation. Such selection causes thegrouping button41 to be enabled, as shown instep92, so that the user may activate it (step93). Activation causes thequery model26 to be updated to reflect new grouping of conditions, as represented instep94. The GUI-Model Infrastructure28 is notified of query model change instep95 and in response, GUI-Model Infrastructure28 updates User I/F20 as shown instep96.
• The Where Clause user interface design proved a challenging undertaking. The current design provides a tremendous amount of functionality masked by a simple and intuitive user interface. Many query builders do not support the full syntax of the Where Clause in the GUI due to the complex nature of this clause, and the inventors are not aware of any that provide the functionality of the present invention.
• A Where Clause consists of a search condition that limits the number of rows the database will return after executing a SQL query. A search condition, which may be nested, consists of a set of predicates combined with logical operators. Each predicate, which may be negated, specifies a condition that may be true, false or unknown. There are many types of predicates that may be expressed using a different syntax for each.
• The Where Clause user interface design of the present invention allows the user to build the search condition one predicate at a time. It allows for easy creation, insertion, nesting, negation and removal of predicates. It supports most of the different forms of predicates available. It allows the user to insert each predicate anywhere in the search condition.
• To make the search condition more readable and understandable, the predicates are indented to show the level of nesting. This flexible design is not only applicable to a Where Clause in SQL, but it may be applied anywhere one has a need to build a potentially nested object (search condition in this case) which is made up of other well-formed, complex objects (predicates in this case).
• Moving on, the “SQL code” editingwindow38 displays the query substatements as they are built and confirmed. Confirmation occurs, e.g., by clicking on “>”button39 with a mouse, and causes the underlying query model to be populated or updated with the new/updated query substatement as previously described.
• Editingwindow38 allows the user to directly modify the displayed query statement, and on completion, to update the query model. Updating is effected by clicking on “Check”button42 or similar means. The user also has the option of undoing his edits by clicking on “Undo Edit” button40, or running the displayed query by clicking on “Run”button44.
• FIG. 3C is a flow chart representing typical user interactions and interface behavior to add or replace a predicate. As represented byblock81, the user first selects a column from theColumn field33. TheColumn field33 is populated with the selected column as repreented inblock82. The user then selects an Operator from the Operator field35 (block83). Inblock84, theOperator field35 is populated with the selected operator and the area below theOperator field35 changes. This allows the user to enter the appropriate type of information for the selected operator, as represented by theloop including block85 anddecision diamond86.
• Next, the user presses one of the center buttons to either insert or replace the predicate in thePredicate area34 into the Search condition area as follows.
• The insert buttons, “AND>”31A and “OR>”31B, are enabled (block87) if the predicate in thePredicate area34 is complete and any line is selected in theSearch condition area36. Pressing these buttons (block88) adds two lines to theSearch condition area36 after the selected line. The first is either the logical operator AND or OR, respectively. The second line added to the Search condition area is the predicate in thePredicate area34.
• The replace button, “>”39, is enabled (not shown) anytime a predicate is selected in theSearch condition area36 or theSearch condition area36 is blank. As represented generally inblock89, if pressed when a predicate is selected in theSearch condition area36 and the predicate in thePredicate area34 is complete, the selected predicate in theSearch condition area36 is replaced with the predicate in thePredicate area34. If button “>”39 is pressed when theSearch condition area36 is blank and the predicate in thePredicate area34 is complete, the predicate in thePredicate area34 is added as the first predicate in theSearch condition area36. If button “>”39 is pressed when theSearch condition area36 is blank and the predicate in thePrediate area34 is incomplete, a message will appear indicating that the user must first complete the predicate.
• Pressing the replace button “>” also causes the query model to be updated, as further indicated byblock89.
• As noted above, many more user interactions can occur on this panel such as nesting, negating and removing predicates..
• III. Parsing a Query
• What is described next is a program algorithm for resolving column references and value expression datatypes in a parsed query language statement, an SQL statement for example. The process involves three phases: syntactic parsing, resolution of table and column references, and resolution of all other value expressions. Each phase operates on a model of the syntactic structure of the QUERY LANGUAGE statement.
• A query parser can handle the syntactic aspect of parsing a query language string by using information contained in the input query string alone. However, the parser cannot handle some of the more semantic aspects of parsing without extra information that is not contained in the query language statement itself. These semantic aspects include associating column references that are contained in the query language with the tables to which the columns belong, and assigning a datatype to each value expression contained in the query language. Value expressions include column references, literal values such as 2 or ‘Smith’, numeric expressions such AGE+10, string expressions such as LASTNAME CONCAT’, ‘CONCAT FIRSTNAME, and the like.
• The three phases of the process are defined as follows.
• Phase 1
• In the first phase, the input QUERY LANGUAGE string is syntactically parsed into an internal model form. As will be described subsequently, the model used is a tree-structured representation of the syntactic elements of the QUERY LANGUAGE statement. For example, the following QUERY LANGUAGE statement,
• • SELECT NAME, SALARY*0.05 FROM EMPLOYEES
• can be represented in model form like this:

  	SQLQueryStatement
  	SQLSelectClause
  	SQLExpressionColumn (name: NAME)
  	SQLExpressionCombined (operator: *)
  	SQLExpressionColumn (name: SALARY)
  	SQLExpressionLiteral (value: .05)
  	SQLFromClause
  	SQLTableReference (name: EMPLOYEES)

  
  where each named item represents a syntactic element of the SQL statement. The indentation above indicates a “contains” relationship. For example, a SQLQueryStatement element contains a SQLSelectClause and a SQLFromClause, and a SQLSelectClause contains a SQLExpressionColumn and a SQLExpressionCombined and so on.
• At the same time that the parser is producing this tree-structured model, it builds a simple list that contains references (or pointers) to the value expressions that it encounters. For the example after the SQL above is parsed, the value expression list contains the following elements.
• • SQLExpressionColumn (name: NAME)
  • SQLExpressionCombined (operator:*)
  • SQLExpressionColumn (name: SALARY)
  • SQLExpressionLiteral (value: 0.05)
  • SQLExpressionTable (name: EMPLOYEES)
    Attributes of the elements are shown in parenthesis following the element name. For example, the SQLExpressionColumn element has an attribute “name” with the value “NAME”.
    Phase 2
• In the second phase of the process, the value expressions that are of type SQLExpressionTable and SQLExpressionColumn in the expression list are semantically resolved by associating them with table (or view) and column entities in a provided information catalog. (In a typical scenario this catalog is the relational database in which the SQL statement is intended to be executed.) First, expressions of type SQLExpressionTable are matched with table entities in the catalog based on attributes of the SQLExpressionTable, such as table name and schema name (if present). Next, information about the columns belonging to each table are obtained from the catalog. This information includes not only the column names, but their datatypes as well (such as INTEGER and VARCHAR). Then, using the column name attribute of the SQLExpressionColumn objects, the SQLExpressionColumns are associated with their corresponding table and column entities in the catalog. This enables datatypes to be assigned to each SQLExpressionColumn. For example, in the query above, afterphase 2 the column expression objects in the model (and in the expression list) have been updated to become:
• • SQLExpressionColumn (name: NAME, table: EMPLOYEES, datatype: VARCHAR(20))
  • SQLExpressionColumn (name: SALARY, table: EMPLOYEES, datatype: DECIMAL(7,2))
    Phase 3
• In the third phase, all remaining value expressions in the expression list are resolved as to their datatype. The technique used to do this varies depending on the kind of value expression and on the type of query structure that contains it. Here are illustrations of the processing required in this phase for several types of value expression.
• SQLExpressionLiteral: the datatype is determined by inspecting the value directly. For example a simple numeric value becomes INTEGER. A decimal value gets the datatype DECIMAL(precision, scale) where the precision and scale are determined by length of the decimal value and the location of the decimal point. A quoted string value gets datatype VARCHAR(length) where the length is the length of the value inside the quotes.
• SQLExpressionCombined: the datatype is determined by recursively examining the left and right side components of the expression object to find a value expression whose datatype has already been resolved, and using that datatype for the datatype of the SQLExpressionCombined object as a whole. For example, if the SQLExpressionCombined encompasses “SALARY*0.05”, the datatype of the expression can be determined by looking at the left side, which contains a SQLExpressionColumn object (SALARY) whose datatype (DECIMAL) is known. The semantic check that the two sides of a combined expression are “combinable” datatypes can be done at the same time.
• SQLExpressionFunction: The method for determining the datatype of a SQL function object varies depending on the particular function involved. For some functions, the datatype is simply the return datatype defined for the function (such as the return type INTEGER for the cast function INTEGER( )). For other functions, the datatype of the function depends on the datatype of its arguments. (For example, the function MAX takes on the datatype of its argument. The datatype of MAX(SALARY) is DECIMAL, while the datatype of MAX(AGE) would be INTEGER.)
• Resolving the datatypes of all the value expressions may take several passes through the value expression list. For the query given above, the expression list at the end ofphase 3 might look like this:
• • SQLExpressionColumn (name: NAME, table: EMPLOYEES, datatype: VARCHAR(20))
  • SQLExpressionCombined (operator:*, datatype DECIMAL(7,2))
  • SQLExpressionColumn (name: SALARY, table: EMPLOYEES, datatype: DECIMAL(7,2))
  • SQLExpressionLiteral (value: 0.05, datatype DECIMAL(2,2))
  • SQLExpressionTable (name: EMPLOYEES)
    IV. Model Content Provider
• The GUI Model Infrastructure (GMI) of the present invention is shown inFIG. 4. It is preferably a software architecture represented byfunctional block28 and resides between theuser interface20 and thequery model26.
• More specifically,user interface20 is shown to include a plurality of GUI API's, GUI API1 and GUI API2. GUI Applications A, B, C and D run on the user interface and are written to a specific GUI API. For example, as shown, GUI applications A and B are written to run on GUI API1. Similarly, GUI applications C and D are written to a different GUI API2.
• TheGMI28 includes Model Content Providers (MCP)111, which translate Query Model (QM)26 information into collections of information that are independent of structure type. The MCP interfaces with Content Viewers113 (CV's118,119,120) which take the MCP collections and manipulate the collections for specific structures such as tables, trees, lists, etc. The CV's113 are a hierarchical set of classes, from the moreabstract structures120 at the top, to the GUI-specific structures118,119 at the bottom.
• The Non GUI API specific components of theGMI28 reside to the right of the dashed line and are created w/o regard to which GUI API will be used. The beauty of this architecture is that the non-specific CV's113 are reusable, API-independent components. Thus, they provide scalability to diverse, subsequently added GUI API's.
• In contrast, the GUI-specific CV's118,119 to the left are written specifically to the GUI API they communicate with. In the presentFIG. 4,CV118 comprises wrapper code forAPI1, andCV119 comprises wrapper code forAPI2. Each GUI Application A, B, C and D interfaces with a GUI-specific CV118,119, informing the CVs about user actions. This approach enables any new GUI application using the same GUI API to reuse the same wrapper code. A new GUI application using a different GUI API can write its own wrapper code and still reuse the common, more abstract, GUI APIindependent Content Viewers120.
• Stepping back for a moment, thecontent viewers113 of the present invention are defined by a hierarchical set of classes. Previously, content viewers were designed for a single GUI API as might be represented byblocks118 and120.
• Due to the lower levels of this hierarchy being GUI API specific, and the higher levels of the hierarchy being non GUI specific, the designers were able to clearly divide theContent Viewers113 into reusable and non reusable components able to support multiple API's. Lower level GUI API specific classes were rewritten to enable reuse of the higher levels of the Content Viewer classes as well as the tightly coupled Model Content Providers.
• TheModel Content Provider111 of the present invention performs several functions. It creates objects, called item providers, that are instances of the model elements representing the current SQL Statement. These objects are created dynamically as the user builds the statement. The query model relationships (e.g. hierarchy, dependencies, etc.) that theQuery Model26 contains are also contained in the item provider objects. Thus, for a specific statement, its “model” is actually a set of item provider objects whose relationships are dictated by theoverall Query Model26.
• MCP111 obtains information from theQuery Model26 and translates this information into data for use by Content Viewers. The higher layers of the Content Viewers, block120, passes on this data to lower layer viewers (blocks118 or119). It receives information from the GUI applications via the Content Viewers, independent of the specific structure (e.g. table, tree, list, etc) of the data.
• In addition,MCP111 is able to discern if the information it gets from the viewers is an addition, a modification, or a deletion of any element in the current model. In the case of an addition, the MCP is able to discern if additional model elements need to be created. It has a “factory” class that takes care of creating additional item providers corresponding to these new model elements. For example, the GUI application gave a request to add a table to the query. One of the content viewers passes this information to theMCP111. TheMCP111 is aware that it will need to get the “children” of this model element, so it calls on its “factory” class to create the children of this particular model element, a table, which happen to be the columns of the table. Once these elements are created and properly linked in theQuery Model26, the MCP instructs the Content Viewers to refresh the information that they have. Only the Content Viewers affected by the addition of the table, will be refreshed. Once refreshed, the Content Viewers will inform the GUI application to update what is displayed to the user.
• Similarly, in the case of a deletion, when a model element that has children is deleted, the Content Viewers send the request to delete this element to theMCP111. TheMCP111 takes care of determining where the child elements are linked to in the entire query model and performs the removal of these objects from theQuery Model26. Again, when the deletions are complete, theMCP111 informs theContent Viewers113 to refresh themselves.
• The MCP provides both data and image information to the viewers. Special classes, called label provider classes contain text and image information and are tied to specific model elements of the query. This allows for easy translation of labels or revision of icons.
• To save an existing query, the Query Assist tool of the present invention provides a set of hierarchical models for storing the query elements, as will be described subsequently.
• V. The Query Model
• The query model of the present invention is designed with the actual syntax of the query language in mind, mirroring each element of the query statement and its relationships to the other elements. Since a number of dialects of a query language such as SQL may be in use, the model is optionally designed to reflect syntax common for multiple dialects. Further, it provides a more detailed representation of query components than is currently available. To this end, detailed representations of various query components are provided.
• FIG. 5 is a flow diagram illustrating the steps for modeling elements of a query according to the present invention
• The present invention provides both a modeling methodology and examples of actual models produced using the described methodology. Once a query element has been selected for modeling, the steps outlined inFIG. 5 are followed to create a tree structure representative of that element. In afirst step41, at least one type associated with the query element is identified. Next, a “parent” node representing the element is defined instep42, and instep43, a “child” node is defined for each identified type. Thereafter, each child node is examined instep44 to determine if it has any subtypes, and if so, a child node of that node is defined for each determined subtype instep45. This process may continue for as many levels of the tree structure that the modeler desires. By proceeding until no further subtypes remain, as represented by theloop including steps44 and45 anddecision diamond46, a highly granular query model is obtained.
• FIGS. 6A-10 provide examples of actual model representations of various elements of a query.
• A. Combined Structures to Represent Query Elements
• A first challenge to the modeler is to completely and accurately depict the iterative and nesting capabilities of the query language. In particular, a query statement may contain a complex query expression that includes an atomic query element “AQE”, i.e., noniterative and unnested query element. It may further include a combined operator “CO”. The CQE includes right and left subelements related by a combined element operator. These subelements may in turn be either AQE's or CQE's, and furthermore, the structure of a CQE is shown below:
  CQE=((LQE CO RQE)
  where LQE is the left query element, RQE is the right query element, CO is a combined operator such as AND/OR, and where LQE and RQE can either be atomic or combined query elements.
• Previous models have often been simplistic and inefficient at representing such expressions, and have therefore been of limited usefulness. This present invention provides a representation that succinctly and accurately reflects the true picture of both the data and underlying structure of the query language.
• Accordingly, the present invention provides a “Combined Structure” model as shown inFIG. 6A to represent complex query. The structure includes an abstract “superclass” shown asparent node51 and first andsecond classes52,53 to represent, respectively, the atomic and combined query elements.
• As an example, consider the following query:

  SELECT DEPARTMENT.DEPTNAME, EMPLOYEE.LASTNAME
  FROM DEPARTMENT, EMPLOYEE
  WHERE
  DEPARTMENT.DEPTNO IN (‘D01’, ‘D11’, ‘D21’) AND
  (EMPLOYEE.SALARY > 50000 OR
  EMPLOYEE.JOB = ‘MANAGER’)

• We will use the above example to map a query into an instance of the model structure shown inFIG. 6A. The statement “WHERE DEPARTMENT.DEPTNO IN (‘D01’, ‘D11’, ‘D21’) AND (EMPLOYEE.SALARY>50000 OR EMPLOYEE.JOB=‘MANAGER’,” is the query element to be modeled and will be represented by an instance ofparent node51. The clause “DEPARTMENT.DEPTNO IN (‘D01’, ‘D11’, D‘21’) is an atomic query element or subclass (AQE) and is represented by an instance ofnode52. The clause “(EMPLOYEE.SALARY>50000 OR EMPLOYEE.JOB=‘MANAGER’)” is an example of a combined query element or subclass (CQE) within that statement and is represented by an instance ofnode53. The atomic and combined query elements are related by a combined operator (CO), in this instance “AND”. Thus, the query element to be modeled may be represented as:
• • WHERE CQE₁
    CQE₁has the following internal structure:
  • AQE₁CO₁CQE₂
    As previously noted, the combined query element's subelements (LQE and RQE, above) may in turn be either AQE's or CQE's. In the present example, the subelements of CQE₂are “EMPLOYEE.SALARY>50000” and “EMPLOYEE.JOB=‘MANAGER’ which can be represented as AQE₂and AQE₃, respectively, and are related by another combined operator “OR”. Accordingly, the present example may further be represented as:
  • WHERE AQE₁CO₁(AQE₂CO₂AQE₃)
    The representation of the example query above is depicted inFIG. 6B.
• According to the present invention, the generalized combined structure ofFIG. 6A may be used at any level of the model's hierarchy to represent the existence of an atomic subclass and a combined query related by a query operator element. The iterative nature of this structure thus provides a simple and intuitive representation of what in the past has been considered a very complex query structure.
• B. Representing Predicates
• FIG. 7 is an exemplary query model representation of a predicate. It includes numerous aspects of a predicate statement, and consistent with the modeling methodology of the present invention, takes into account multiple SQL dialects and proper syntax.
• C. Representing Table References
• FIG. 8 is an exemplary query model representation of a table reference. It clearly represents all desired aspects of the table reference query element. And consistent with the modeling methodology of the present invention, it takes into account multiple SQL dialects and proper syntax.
• D. Representing Value Expressions
• FIG. 9 is an exemplary query model representation of a value expression. It includes all desired aspects of the value expression query element and takes into account multiple SQL dialects and proper syntax.
• E. Representing Group-By
• FIG. 10 is an exemplary query model representation of a group-by statement. It includes numerous aspects of the Group By query option, including advanced features. And consistent with the modeling methodology of the present invention, it also takes into account multiple SQL dialects and proper syntax.
• F. Generating a Query Language Element from the Query Model Inclusive of its Children
• An advantage of the top-down modeling approach of the present invention is the ability to recreate any query language element such as a clause or substatement of the query downward, not just at the root level. That is, a call can be made to a particular subnode, and as a result of the call the subnode and its children return a reconstructed query language element representing the value of the subnode and its children.
• As an example, consider the following select statement:
• • SELECT NAME, DEPT, SALARY+BONUS FROM EMPLOYEES
    A call may be made to the subnode of the model that represents the third result column of the select clause of the query and as a result, the “SALARY+BONUS” query language element would be reconstructed and returned. The portion of the model instance that represents the third result column is shown inFIG. 11. A call to the model element or node representing SQLResult returns the query statement for that element of the statement, i.e., the query element and all of its children.
    G. Maintaining Model Independence Within a Larger Collection of Models
• Applications may involve multiple models which may have a domain different from the one described above. This can be a problem when there are dependencies between models so that even minor changes to one model can affect the other models and require updating to the latter. More specifically, in a typical code generating environment, when models used to generate code have dependencies between them, then modifying one model requires code to be regenerated for all the related models.
• The present invention helps to overcome this problem by providing a greater degree of independence among models. Within the code-generating environment, dependencies between models are removed such that changes to one model do not force the regeneration of code by other models.
• This is achieved by adding proxy objects to a model to replace references to other models, and then reestablishing the references amongst the models after the code generation step.
• An example is illustrated inFIG. 12.Model1 needs to reference an element of model2 (“ClassC”). Instead of creating a reference directly fromModel1 to ClassC inModel2, an extra element Class3_C is added toModel1 that tales the place of ClassC. Therefore all references are contained within Model1. After code is generated from the models, the generated code is modified to connect element Class3_C and ClassC. This is shown with the dotted line inFIG. 12.
• Although the present invention has been described with reference to a specific embodiment, various substitutions and modifications may occur to the developer in implementing the invention without departing from its spirit and scope. Accordingly, the invention is not to be limited by the specification set forth, but is to be accorded its broadest interpretation as claimed, below.

Claims (36)

1. A query assist tool providing a dynamically adaptive interface for creating a query search condition, comprising:

means for displaying selectable columns of a table in a first display area;

means for displaying selectable query operators in a second display area; and

means responsive to selection of an operator,for displaying selectable options for the selected query operator in a third region.

2. The query assist tool ofclaim 1, further comprising means for displaying a resulting search condition in a fourth display area after selection of a column, an operator, and an option.

3. The query assist tool ofclaim 1, further comprising means for confirming a selection of a column, operator, and operator option.

4. The query assist tool ofclaim 3, further comprising means for displaying a resulting search condition in a fourth display area in response to a selection confirmation.

5. The query assist tool ofclaim 3, wherein the means for confirming a selection further comprises one or more of the group consisting of: a selectable button in a fifth display region, a mouse click, a keystroke, and an equivalent of any of the foregoing.

6. The query assist tool ofclaim 1, further comprising means for providing a resulting search condition to a query model.

7. The query assist tool ofclaim 1, the user interface further comprising means for receiving at least a portion of query statement, and means for displaying elements of the received query statement in a fourth display area.

8. The query assist tool ofclaim 1, further comprising means for receiving query elements from a query model instance.

9. The query assist tool ofclaim 1, further comprising means for receiving at least a portion of a query statement from an application.

10. The query assist tool ofclaim 1, wherein the means for displaying selectable columns further comprises means for providing a pull-down menu of selectable column names.

11. The query assist tool ofclaim 1, wherein the means for displaying selectable operators further comprises means for providing a pull-down menu of selectable operators.

12. The query assist tool ofclaim 1, further comprising means for displaying selectable operators for connecting a plurality of created search predicates in a fourth display region.

13. A method for providing a dynamically adaptive interface for creating a query search condition, comprising the steps of:

displaying selectable columns of a table in a first display area;

displaying selectable query operators in a second display area; and

in response to selection of an operator, displaying selectable options for the selected query operator in a third region.

14. The method ofclaim 13, further comprising the step of, after selection of a column, an operator, and an option, displaying a resulting search condition in a fourth display area.

15. The method ofclaim 13, further comprising the step of providing means for confirming a selection of a column, operator, and operator option.

16. The method ofclaim 15, further comprising the step of displaying a resulting search condition in a fourth display area in response to a selection confirmation.

17. The method ofclaim 15, wherein the means for confirming a selection further comprises one or more of the group consisting of: a selectable button in a fifth display region, a mouse click, a keystroke, and an equivalent of any of the foregoing.

18. The method ofclaim 13, further comprising the step of providing a resulting search condition to a query model.

19. The method ofclaim 13, further comprising the step of receiving at least a portion of a query statement, and displaying elements of the received query statement in a fourth display area.

20. The method ofclaim 13, further comprising the step of receiving elements of a query from a query model instance.

21. The method ofclaim 13, further comprising the step of receiving at least a portion of a query statement from an application interface.

22. The method ofclaim 13, wherein displaying selectable columns further comprises the step of providing a pull-down menu of selectable column names.

23. The method ofclaim 13, wherein displaying selectable operators further comprises the step of providing a pull-down menu of selectable operators.

24. The method ofclaim 13, further comprising the step of displaying selectable operators for connecting a plurality of created search predicates in a fourth display region.

25. An article of manufacture comprising a computer program carrier readable by a computer and embodying one or more instructions executable by the computer for providing a dynamically adaptive interface for creating a query search condition, the computer program comprising:

program instructions for displaying selectable columns of a table in a first display area;

program instructions for displaying selectable query operators in a second display area; and

program instructions for displaying selectable options for the selected query operator in a third region in response to selection of an operator.

26. The article of manufacture ofclaim 25, further comprising program instructions for displaying a resulting search condition in a fourth display area after selection of a column, an operator, and an option.

27. The article of manufacture ofclaim 25, further comprising program instructions for providing means for confirming a selection of a column, operator, and operator option.

28. The article of manufacture ofclaim 27, further comprising program instructions for displaying a resulting search condition in a fourth display area in response to a selection confirmation.

29. The article of manufacture ofclaim 27, wherein the means for confirming a selection further comprises one or more of the group consisting of: a selectable button in a fifth display region, a mouse click, a keystroke, and an equivalent of any of the foregoing.

30. The article of manufacture ofclaim 25, further comprising program instructions for providing a resulting search condition to a query model.

31. The article of manufacture ofclaim 25, further comprising program instructions for receiving at least a portion of a query statement, and program instructions for displaying elements of the received query statement in a fourth display area.

32. The article of manufacture ofclaim 25, further comprising program instructions for receiving query elements from a query model.

33. The article of manufacture ofclaim 25, further comprising program instructions for receiving at least a portion of a query statement from an application interface.

34. The article of manufacture ofclaim 25, wherein the program instructions for displaying selectable columns further comprise program instructions for providing a pull-down menu of selectable column names.

35. The article of manufacture ofclaim 25, wherein the program instructions for displaying selectable operators further comprise program instructions for providing a pull-down menu of selectable operators.

36. The article of manufacture ofclaim 25, further comprising program instructions for displaying selectable operators for connecting a plurality of created search predicates in a fourth display region.

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